Rotor for centrifugal blowers



w. EVANS ROTOR FOR CENTRIFUGAL BLOWERS Feb. 11, 1941.

Filed Sept. 15, 1939 j ,IIIIIIIIIIIIIIIIII'IIII.

III'IIJIII/IIIIIIII'IIA INVENTORI ADDISON w. EVANS W ATTORNE Patented Feb. 11,1941

UN lT ED STATES PATENT OFFICE 2,231,063 ROTOR FOR CENTRIFUGAL BIOWERS Addison W. Evans, Torrlngton, Conn.,assignor to The Torrlngton Manufacturing (70., Torrington, Conn, a corporation of Connecticut Application September 13, 1939. Serial No. 294,626

3 Claims. (Cl. 230-134) The present invention relates particularly to that typg of centrifugal blower wheel, sometimes 1 designated as a rotor or impellerfor centrifugal blowers, in. which the body portion of the wheel, which is of substantially cylindrical form, is initially formed up of a single or only a few strips oflsheet metal, and wherein, say a single such strip, is slltted incompletely in a direction transversely of the length of the strip, the individual blade elements being then formed up from the metal between the adjacent, substantially parallel slits. This practice is ormay be in accordance with that outlined in my' copending .ap-

plication first above referred to. In blower wheels of this generaltype it isoften the case that the curved blade-forming body is of sheet metal of a somewhat lighter gauge than the-back plate or end ringelements which serve to support the blade-carrying strip at its opposite margins.-

'Heretoi'ore the assembly securement of the blade portions of the wheel has been usually eifected by welding, or by the use of individual rivets,

with the result that the dynamic and running balance'of the wheel structure is not always satisfactory without extra balancing operations. This is due in part to the personal equation incident to manual assembly operations, and in part to inequalities in rivets or other securing metal elements or exp'edients. Accordingly, the

- present invention has ,as its major object, the

general-improvement of blower wheels or centrifugal rotors of the general type above discussed, such improvements resulting in a better balance, a greater certainty of uniform securement of the blade-carrying body to the end rings or like elements, a well as a reduction in production cost, all without increasing undesirably any of the dimensions of the blower wheel or rotor incident to usage of the assembly and securement expedients to be described.

The present invention may be briefly referred to as an. arrangement involving the use of sepresent improvements; Fig. 2 is an enlarged fragcurement means integral with one of the very few elements of the wheel, and accordingly a further object is attained in..avoidance of many of the former dimculties, arising out of assemblies embodying separate rivet elements, and in assuring 5 that the securement portions of the wheel parts are uniformly spaced so as to assure good balance, and that the blades are in all cases parallel and uniformly arranged at the correct angle in the wheel.

Yet another object of the invention, somewhat related to those heretofore mentioned, is attained in an arrangement of assembly members or elements integral with the major parts of the wheel or some thereof, providing a novel and simple means for securement of the blade structure to the back plates or end rings in a uniform manner throughout-the wheel so as to insure a good running and dynamic balance without requiring any extensive ancillary balancing operations.

The foregoing and numerous other objects and advantages of the invention will be readily apparent from the following detailed description of certain preferred embodiments of the-invention, considered in connection with the accompanying drawing, in which: I

Fig. 1 is an elevation in perspective of a centrifugal blower wheel of a :type embodying the mentary end view, showing a portion of a bladeforming strip of the wheel, near one end thereof; Fig. 3 is a. fragmentary end elevation of the periphery of one of the end rings, this view including azsection of one of the integral securement elements of the body; Fig. 4 is a fragmentary section, taken in a radial plane, show-- ing one end portion of the blade carrying strip or 'body, and the adjacent portion of one end ring; Fig. 5.is a view corresponding generally to Fig. 2, but showing a, somewhat modified form of assembly; Fig. 6 is a view taken similarly to Fig. 3 illustrating the modification, and Fig. 7 is a fragmentary radial section taken after the manner of Fig. 4, but illustrating the modification .shown in part by Figs. 5 and 6.

Referring by characters of reference to the drawing, the assembled wheel comprises, by preference, a'pair of spaced annular end elements, one of which is, for example, an end ring indicated generally at 10. It will be understood by those skilled in the art that one of the end elements may consist of a relatively open end ring such as shown, while, if desired, the opposite end of the wheel may be constituted by a relatively ings l2 for securement of" this disc to a hub (not shown) which in turn may be keyed or secured by a set screw or the like to the mounting shaft which is omitted from the assembly of Fig. l for clearness of illustration. Projecting radially from the disc portion ii are a plurality of arms or spokes l3, and the outer ends of the spokes extend into and serve to carry a substantially planar rim it which serves, as will later more clearly appear, as the immediate support for the blade-forming body.

According to the present design and by preference, the end rings I 0 are so formed as to lie closely in a given plane transverse of the axis of rotation. This substantially flat arrangement of end rings, taken with the fact that the assembly expedients to be described do not add appreciably to any dimension of the wheel, assures against any increase particularly in axial dimension or length of the wheel as a result of the special securing expedients characterizing the invention.

The substantially cylindrical body element of the wheel, from which the blades are formed and by which they are carried, is or may be similar in all important respects to that shown and described in my copending application first above cited, the present improvements relating chiefly to a modified method of securement of the margins of the blade -carrying strip or body to the end rings or plates. Since the general method of blade formation is fully described in the copendlng application first above noted, it need be presently described in no more detail than to mention as a preference that thebody lies substantially in a curved plane generally resembling the surface of a cylinder. Either'by one or a series of punching or stamping operations the individual blades are formed in the initially fiat strip by slitting the strip in a direction transversely thereof with the slits in substantially parallel relation so that the bodyforming element when thus punched, is itself characterized by a plurality of parallel, transverse, adjacent strip portions, the body portion generally being indicated at 19 and the' initial locations of the slits at 20 and 2| for any given one of the blades. The metal between the slits 20, 2! is, in whole or in part,'*bent out of the plane of the strip so as to form each blade to a substantially arcuate section on a relatively small radius. from which it results that the fin- -ished rotor is characterized by a plurality of the spaced blades 23. I

As will be apparent from Fig. 2, the individual blades 23 do not extend entirely across the body strip; but terminate inwardly of its lateral margins so as to'leave impe'rforate the side marginal area on the body strip, such as indicated: generally at 24 (Fig,. 2). This marginal area provides a somewhat circular flange at each end of the series of formed blades.

0n the extreme margin of each of the areas 24, is. provided a series of lugs or tongues 25.

These are preferably initially formed on the mar- S ns of the strip according to the arrangement of Figs. 1, 2, 3 and 4, incident to anyone of the operations which serve to shape the body strip or to form up the blades thereon. -As initially provided, these tongues 25 are of the shape best shown at the upper'left hand portion of Fig. 3, and are distinctly elongate in section in a direction circumferentially of the wheel, so that the width of each tongue preferably substantially exceeds the thickness or gauge thereof, which latter will usually correspond with the gauge of the metal of the body strip Hi. It is a further preference in forming the tongues, that each thereof along the given margin of the body-forming strip, beformed by the same dies, with the strips subjected to an indexing operation, so that the tongues or lugs 25 are all initiallyof the same width and length, and all project to the same extent from the margin 24. It will have appeared that the tongues or lugs 25 serve as integral assembly expedients or assembly elements, hence the uniformity in size and shape as assured by the practice noted, conduces to an improved degree of dynamic and running balance in the completed wheel.

According to the arrangement above illustrated by Figs. 1, 2, 3 .and 4, the end rings or back plates typified by the end ring ii), are each provided with an annular series of rectangular slots, formed as by a punching and indexingvoperation, the individual apertures being indicated at 26. It is of great preference that these slots be of a size or area closely conforming to the cross section of the individual lugs 25, it being apparent that in assembly the end rings are first presented to the strip 23 with the openings 26 in register with the several corresponding lugs 0r tongues 25, then applied to the strip in such mannet that the tongues project through and slightly yet evenly beyond the apertures.

After initial assembly of the end plates to the body 23, the tongues 25 project slightly beyond the outer end face of the peripheral portion I4 of the end ring. The projecting tongues or lugs are then subjected to a high rolling pressure, or if preferred, an impacting operation for the purpose of upsetting this projecting metal and expanding it in the region of the corresponding apertures 26wlth the effect of firmly securing projection forms a shoulder against which the ring periphery I4 is seated in assembly, with advantages during the operation of the upsetting the projecting ends of the tongues or lugs 25 and thereafter.

It is my preference in design that the numher and width of the tongues 25 be such that the transverse sectional extent or width thereof, slightly exceeds the area intervening the tongues and openings 26. It results from this that when the assembly operation is completed by upsetting operations on, or deformation of, the ends of the-tongues, the body strip of the rotor or wheel is secured to the adjacent end ring over substantially the greater part of a circular zone corresponding to its lateral margin.

A slight modification of the structure heretofore described, although one in which embodies the same essential principles, is shown by Figs. 5, 6 and 7. In the latter arrangement the bladecarrylng body strip ISA is characterized by blades 23A and provided with an imperforate lateral margin 24A, there being one of these areas at each end of the series of blades. However, instead of this margin being punched to provide the tongue or lugs forsecurement, it is provided with a series of apertures 25A somewhat inwardly of the free-edge 21A of the blade-carrying strip.

The modification is further distinguished by one or more end rings or back plate elements which may be in all important respects similar to the end rings H) of Fig. 1, except characterized by a modified periphery A which, for example by punching, is formed'to provide an indented outer edge characterized by radially projecting rectangular tongues 28A. These usually are of somewhat heavier gauge than the projections 25 because of the greater thickness of metal from which the end rings are formed, and for this reason the openings 25A in the body strip will be of somewhat greater width in the modified form. However, it is preferred that the number and spacing of the peripherally projecting row of tongues or lugs 28A correspond in general to that above described in reference to the tongues 25 of Fig.2.

In the modified form of assembly, the end ring portion NA is provided with an inwardly projecting annular shoulder 30A, against which the body strip is firmly seated with the projections 28A extending through the registering apertures 25A. With the parts thus located, a heavy rolling pressure against the projecting ends of the tongues or lugs 28A serves to upset or deform the projecting metal tongue ends against the outer face of the marginal portion [9A, of the body strip, which is thus held snugly embraced between the substantial areas of deformed metal on the outside, and the annular shoulder 30A on the inside.

It will appear that either of the assembly expedients herein described, results in a rigid, sub stantial wheel structure, which obviates entirely the necessity for brazing, welding or soldering operations, thus resulting in an extremely low cost assembly. It will have further appeared that making somewhat specific reference to certain preferred'embodiments, it is to be understood that numerous changes may be made in the parts, their combinations and assembly, without departing from the-intended scope of the invention as defined by the appended claims.

I claim:

1'. In a centrifugal blowerwheel, a one-piece end ring member, acne-piece, substantially 037- r the other member being marginally provided with a row of apertures, each of a size to receive and closely to embrace one of the tongues, the tongued member being provided with a substantially continuous rib, forming an annular seat for the apertured member, and located close to the tongues, the ends of the tongues being deformed in holding engagement with the adjacent face of the apertured member, and said ends coacting with the annular seat for closely embracing the apertured member and for securement of the members in assembly.

2. A centrifugal blower wheel including a onepiece cylindrical sheet metal body element apertured and formed to provide a plurality of blades, a pair of spaced end rings bridged by the body element, a plurality of tongues projecting from the lateral margins of the body element, the end rings each being provided with an annular row of apertures corresponding substantially in size and position to said tongues, the body element further being provided with a substantially continuous, circular seat for the end ring, spaced in- .wardly of but close to the -free ends of the tongues, each ring and the body being positioned in assembly by engagement of the ring with said circular seat, and the endsof the tongues being deformed to engage the outer peripheral portion of .the end ring, and thereby secure said portion snugly against the circular seat.

3. In a centrifugal blower wheel, one or more end rings, a one-piece sheet metal, cylindrical body element, apertured and formed to provide a plurality of blades, and provided with a row of apertures along each of its lateral margins, each of the end rings including a plurality of lugs or tongues projecting radially from the periphery thereof, the tongues being of a size, section and of engagement of the body portion with the circular seat.

' ADDISON W. EVANS. 

